Not to be that guy but that's what I figured all along. Young, inexperienced kid, got himself a sling, magazine, ammo, RDS. Might have either skipped the lube altogether or didn't apply it liberally enough as is needed in addition to it being a brand new rifle. I'm pretty sure he mentioned it had only been shot a couple times and it was during a nationwide shortage so I'm sure it didn't get a vigorous break in.
My first thought was brand new gun, probably a bone dry bcg. My first AR many years ago was completely underlubed, I shot it quite a bit pretty much dry. I kind of shudder to think of it now. Some old timers would have you believe that only a drop is needed and don't understand that the AR isn't grandpappy's shotgun and needs liberal amount of lube to be happy. (Reliable).